If the interface is selectable but no system shows up in the dialog "SAP Logon", the file "saplogon.ini" is not findable. Please check the PATH variable for the path of the "saplogon.ini" (usually c:\Users\<Windows username>\AppData\Roaming\SAP\Common\). The path to the saplogon can be found in the Options dialog of the SAP LOGON tool:

If the path to the "saplogon.ini" is not available in the PATH variable a "system variable" called SAPLOGON_INI_FILE can be defined. The variable value should be filled with the path to the saplogon.ini file. A reboot of the computer may be necessary after setting the variable.